01 Silv with erratic blower speed???

**aftershock00** · 08-04-2009, 08:33 AM

Hoping you could help me out here guys...

I purchased an 01 Silverado 5.3 about 2 years ago. Since I purchased it, blower speed #1 has never worked. No big deal.
However, I have been noticing this summer as I have my AC on the higher settings 3,4,5 that out of nowhere, the AC will suddenly begin to blow significantly harder. I will be driving in setting 3 and the ac will blow as if on setting 5. The blower will be substantially louder. Im not 100 sure if the blower is actually blowing harder or if the extra noise is tricking me into thinking it, but im definately leaning towards it being a more powerful air supply.

Either way, what is causing this? Has anyone ever heard of this?
I dont have electronic climate control, but the way the ac begins to blow harder (or how it goes back down to "normal") is as if an electronic temp control is present.

If there isnt an abvious answer, can someone please tell me how to go about troubleshooting it as far as using a light tester, voltmeter, etc?

I think this problem and the lack of #1 setting MIGHT be related. If so, I definately want to get this problem taken care of. Thanks for all the help

**bill190** · 08-04-2009, 09:26 AM

If you have a "blower motor resistor" which would be near the blower motor, check that. Also check the wires/electrical connector to the blower motor resistor.

Full troubleshooting instructions would be in a GM Factory Service Manual set for your year/model vehicle. You can order this from helminc.com or a GM dealer.

Also for troubleshooting electrical problems (and following the factory instructions) you would need to use a multimeter. How to use a multimeter...
http://www.google.com/search?hl=en&s...imeter&aqi=g10

**aftershock00** · 08-04-2009, 01:22 PM

so you dont think it has anything to do with the switch? I figured since speed #1 doesnt work at all, that the switch was bad, and now this erratic fan speed is just the second phase of my already bad fan switch.

Guess my theory is completely wrong?

**azdrtdog** · 08-04-2009, 04:36 PM

BLAH BLAH BLA turn the knob to max when u hear it if the sound does not change its going to high on its own.if it does speed up the increase in noise is most probly the blend door opening and closing (draws air from inside the cab and u can hear the intake from the blower louder) any way my 99 has been doing that for years and it is in the climate control module. hope this helps

**aftershock00** · 08-04-2009, 05:02 PM

yeahhhh....it does sound like something is getting actuated inside the dash.

I see what you're saying about raising it to high and seeing if it goes any higher or not. Thing is...it does go higher. When the blower goes into "turbo mode", all fan speeds SEEM higher than normal. So yes, when its in turbo mode, it does get higher. Kinda like the old school window ac units which had the fan speeds and then a high cool and a low cool.....so fan speed five on low cool was like speed three on high cool, etc etc. Am I making sense here?

**bill190** · 08-04-2009, 06:58 PM

Originally Posted by aftershock00

so you dont think it has anything to do with the switch? I figured since speed #1 doesnt work at all, that the switch was bad, and now this erratic fan speed is just the second phase of my already bad fan switch.

Guess my theory is completely wrong?

No you could be completely right! Switches go bad also.

Just need to test things with a multimeter and find the problem is all. A factory wiring diagram helps.

**azdrtdog** · 08-04-2009, 11:04 PM

all fan speeds will sound louder it opens a direct path from the floor to the blower instead off pulling through cowl(fresh air) put it on recirculate for a while and it should stay the same. mine seems to favor the recir.side and never goes to fresh on its own.(that will make it quieter if it does) the switch only steps the voltage down for low speeds high is a full 13.5V or so with alt. supply dictating the final fan rpm. it wont turbo it past what high can do its just direct at that point and low might have burnt prematurly do to it having to burn off the most juice to get a lower speed

**vncj96** · 08-04-2009, 11:07 PM

I am on board with the blower motor resistor, my wifes car does the exact same thing, and i know her make of car is notorious for this, it happens. i know for my wifes car you just pull out the glove box and there is the resistor, they dont cost that much, way cheaper then getting an entire new HVAC control unit and that doesnt fix it